Predisposing factors, disease progression and outcome in 430 prospectively followed patients of healthcare- and community-associated Staphylococcus aureus bacteraemia.

Staphylococcus aureus bacteraemia (SAB) episodes identified in a prospective multicentre study during 1999-2002 (not including MRSA) were followed up by an infectious disease specialist. The aim of this study was to compare predisposing factors, disease progression and outcome of healthcare (HA)- and community (CA)-associated SAB. Of 430 SAB episodes, 232 (54%) were HA. The HA-SAB patients were significantly older and more chronically ill compared to CA-SAB. Deep infection foci prevalence within three days of onset of SAB for HA versus CA were deep-seated abscesses (26% vs 37%, P < 0.05), pneumonia [25% vs 31%, non-significant (NS)], osteomyelitis (24% vs 36%, P<0.01), permanent foreign body (24% vs 9%, P<0.001), endocarditis (11% vs 15%, NS), septic arthritis (9% vs 13%, NS) and no infection focus (3% vs 6%, NS). The case fatality rates for HA-SAB versus CA-SAB at 28 days were 14% vs 11% (NS). Independent risk factors according to multivariate analysis for a fatal outcome were age, chronic alcoholism, immunosuppressive treatment, ultimately or rapidly fatal underlying diseases, severe sepsis on the onset of SAB, S. aureus pneumonia and endocarditis. As a result of a prospective study design, meticulous infection foci search and infectious disease specialist follow-up of each SAB episode, the case fatality remained low and 97% of the HA-SAB episodes presented infection foci within three days of onset of bacteraemia.